:root {
  --bg: #05060a;
  --bg-alt: #0b0d14;
  --fg: #f5f5f7;
  --muted: #9ea2b3;
  --accent: #ff6b3d;
  --accent-soft: rgba(255,107,61,0.18);
  --accent-strong: #ff8a54;
  --line: #262a39;
  --card-bg: #101321;
  --scene-radius: 26px;
  --shadow-soft: 0 18px 50px rgba(0,0,0,0.55);
}

* {
  box-sizing: border-box;
}

html, body {
  margin: 0;
  padding: 0;
  background: radial-gradient(circle at top, #141726 0, #05060a 48%, #000 100%);
  color: var(--fg);
  font-family: system-ui, -apple-system, BlinkMacSystemFont, "SF Pro Text",
    "Segoe UI", sans-serif;
  scroll-behavior: smooth;
}

body {
  min-height: 100vh;
}

a {
  color: inherit;
  text-decoration: none;
}

/* Basic layout */
header {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  z-index: 100;
  padding: 14px 32px;
  display: flex;
  align-items: center;
  justify-content: space-between;
  backdrop-filter: blur(16px);
  background: linear-gradient(to bottom, rgba(5,6,10,0.92), transparent);
  border-bottom: 1px solid rgba(255,255,255,0.04);
}

header .brand {
  display: flex;
  align-items: center;
  gap: 8px;
}

header .brand-mark {
  width: 26px;
  height: 26px;
  border-radius: 999px;
  background: radial-gradient(circle at 30% 20%, #fff 0, #ffd2c0 24%, #ff6b3d 60%, #8c2d14 100%);
  box-shadow: 0 0 0 2px rgba(255,255,255,0.08), 0 4px 15px rgba(0,0,0,0.6);
}

header .brand-name {
  font-weight: 650;
  letter-spacing: 0.08em;
  text-transform: uppercase;
  font-size: 0.85rem;
}

header nav {
  display: flex;
  gap: 20px;
  font-size: 0.85rem;
  text-transform: uppercase;
  letter-spacing: 0.08em;
}

header nav a {
  position: relative;
  padding-bottom: 4px;
  color: var(--muted);
}

header nav a::after {
  content: "";
  position: absolute;
  left: 0;
  bottom: 0;
  width: 0;
  height: 2px;
  border-radius: 999px;
  background: linear-gradient(90deg, var(--accent), var(--accent-strong));
  transition: width 0.25s ease-out;
}

header nav a:hover {
  color: var(--fg);
}

header nav a:hover::after {
  width: 100%;
}

main {
  padding-top: 72px; /* space for fixed header */
}

/* Hero */
.hero {
  min-height: 70vh;
  padding: 80px 5vw 80px;
  display: grid;
  grid-template-columns: minmax(0, 2fr) minmax(0, 1.3fr);
  gap: 40px;
  align-items: center;
}

@media (max-width: 900px) {
  .hero {
    grid-template-columns: minmax(0, 1fr);
    padding-top: 96px;
  }
}

.hero-kicker {
  font-size: 0.85rem;
  text-transform: uppercase;
  letter-spacing: 0.25em;
  color: var(--accent-strong);
  margin-bottom: 14px;
}

.hero h1 {
  font-size: clamp(2.6rem, 4vw, 3.8rem);
  line-height: 1.1;
  margin: 0 0 16px;
}

.hero p {
  margin: 0 0 22px;
  color: var(--muted);
  max-width: 36rem;
  font-size: 0.98rem;
}

.hero-badges {
  display: flex;
  flex-wrap: wrap;
  gap: 10px;
  margin-bottom: 26px;
}

.badge {
  border-radius: 999px;
  border: 1px solid rgba(255,255,255,0.08);
  padding: 6px 12px;
  font-size: 0.78rem;
  text-transform: uppercase;
  letter-spacing: 0.12em;
  color: var(--muted);
  background: radial-gradient(circle at top left, rgba(255,255,255,0.1), transparent 65%);
}

.hero-actions {
  display: flex;
  flex-wrap: wrap;
  gap: 14px;
  align-items: center;
}

.btn {
  border-radius: 999px;
  padding: 10px 18px;
  font-size: 0.88rem;
  border: none;
  outline: none;
  cursor: pointer;
  display: inline-flex;
  gap: 8px;
  align-items: center;
  justify-content: center;
  text-transform: uppercase;
  letter-spacing: 0.1em;
  font-weight: 600;
  text-decoration: none;
}

.btn-primary {
  background: linear-gradient(135deg, var(--accent), var(--accent-strong));
  color: #0a0503;
  box-shadow: 0 12px 25px rgba(0,0,0,0.7);
}

.btn-primary:hover {
  filter: brightness(1.08);
  transform: translateY(-1px);
}

.btn-ghost {
  background: rgba(255,255,255,0.02);
  color: var(--muted);
  border: 1px solid rgba(255,255,255,0.1);
}

.btn-ghost:hover {
  background: rgba(255,255,255,0.06);
  color: var(--fg);
}

.hero-meta {
  font-size: 0.78rem;
  color: var(--muted);
}

.hero-meta strong {
  color: var(--fg);
  font-weight: 600;
}

.hero-visual {
  position: relative;
  min-height: 260px;
}

.hero-bike-orbit {
  position: absolute;
  inset: 0;
  border-radius: 32px;
  background: radial-gradient(circle at 20% 0, rgba(255,255,255,0.18), transparent 55%),
              radial-gradient(circle at 80% 100%, rgba(255,107,61,0.4), transparent 60%),
              radial-gradient(circle at 50% 50%, #05060a, #020308 75%);
  box-shadow: var(--shadow-soft);
  overflow: hidden;
  border: 1px solid rgba(255,255,255,0.06);
}

.hero-bike-orbit::before {
  /* abstract bike silhouette */
  content: "";
  position: absolute;
  inset: 10%;
  border-radius: 40%;
  border: 1px solid rgba(255,255,255,0.35);
  filter: blur(0.6px);
  opacity: 0.7;
  pointer-events: none;
}

.hero-bike-orbit::after {
  content: "";
  position: absolute;
  inset: 20%;
  border-radius: 50%;
  border: 1px dashed rgba(255,255,255,0.35);
  border-left-color: transparent;
  border-right-color: transparent;
  animation: orbit 14s linear infinite;
  opacity: 0.7;
  pointer-events: none;
}

@keyframes orbit {
  from { transform: rotate(0deg);} 
  to   { transform: rotate(360deg);} 
}

.hero-bike-label {
  position: absolute;
  font-size: 0.7rem;
  text-transform: uppercase;
  letter-spacing: 0.14em;
  padding: 6px 10px;
  border-radius: 999px;
  background: rgba(5,6,10,0.78);
  border: 1px solid rgba(255,255,255,0.12);
  color: var(--muted);
  backdrop-filter: blur(12px);
  z-index: 5;
  display: inline-block;
  cursor: pointer;
}

.hero-bike-label strong {
  color: var(--fg);
  font-weight: 600;
}

.hero-bike-label--crank   { top: 16%; left: 12%; }
.hero-bike-label--lugnut  { bottom: 18%; right: 10%; }
.hero-bike-label--software{ top: 50%; left: 55%; transform: translateY(-50%); }

/* Singletrack scroll section */
.scroll-section {
  position: relative;
  height: 500vh; /* enough scroll distance for 5 scenes */
}

.scroll-container {
  position: sticky;
  top: 72px; /* below header */
  height: calc(100vh - 72px);
  overflow: hidden;
  padding: 24px 0 48px;
}

.ride-track {
  display: flex;
  height: 100%;
  will-change: transform;
  transition: transform 0.05s linear;
}

.scene {
  flex: 0 0 100vw;
  padding: 32px 7vw;
  display: grid;
  grid-template-columns: minmax(0, 1.2fr) minmax(0, 1.1fr);
  gap: 40px;
  align-items: center;
  position: relative;
}

.scene-inner {
  background: radial-gradient(circle at top, #171a2b 0, #090b14 55%);
  border-radius: var(--scene-radius);
  padding: 28px 26px;
  border: 1px solid rgba(255,255,255,0.05);
  box-shadow: var(--shadow-soft);
  position: relative;
  overflow: hidden;
}

.scene-inner::before {
  content: "";
  position: absolute;
  inset: 0;
  border-radius: inherit;
  background: radial-gradient(circle at top right, rgba(255,255,255,0.12), transparent 60%);
  opacity: 0;
  transition: opacity 0.35s ease-out;
  pointer-events: none;
}

.scene.is-visible .scene-inner::before {
  opacity: 1;
}

.scene-kicker {
  font-size: 0.75rem;
  text-transform: uppercase;
  letter-spacing: 0.22em;
  color: var(--accent-strong);
  margin-bottom: 12px;
}

.scene h2 {
  margin: 0 0 10px;
  font-size: 1.6rem;
}

.scene p {
  margin: 0 0 16px;
  color: var(--muted);
  font-size: 0.95rem;
  line-height: 1.5;
}

.scene-list {
  list-style: none;
  padding: 0;
  margin: 0;
  display: grid;
  gap: 8px;
  font-size: 0.9rem;
  color: var(--muted);
}

.scene-list li {
  display: flex;
  align-items: flex-start;
  gap: 8px;
}

.scene-list li::before {
  content: "•";
  color: var(--accent-strong);
  margin-top: 1px;
}

.scene-label {
  position: absolute;
  top: 24px;
  right: 28px;
  font-size: 0.72rem;
  text-transform: uppercase;
  letter-spacing: 0.18em;
  color: var(--muted);
  opacity: 0.85;
}

.scene-meta {
  font-size: 0.8rem;
  color: var(--muted);
  margin-top: 12px;
}

.scene-visual {
  position: relative;
  min-height: 220px;
  border-radius: var(--scene-radius);
  border: 1px solid rgba(255,255,255,0.05);
  background: radial-gradient(circle at top left, rgba(255,255,255,0.12), transparent 50%),
              radial-gradient(circle at bottom right, rgba(255,107,61,0.3), transparent 55%),
              #05060a;
  overflow: hidden;
  box-shadow: var(--shadow-soft);
  padding: 18px 18px 24px;
  display: flex;
  flex-direction: column;
  justify-content: space-between;
}

.scene-visual h3 {
  font-size: 0.9rem;
  text-transform: uppercase;
  letter-spacing: 0.16em;
  margin: 0 0 6px;
  opacity: 0.86;
}

.scene-visual p {
  font-size: 0.83rem;
  margin: 0;
  color: var(--muted);
}

.scene-tags {
  display: flex;
  flex-wrap: wrap;
  gap: 6px;
  margin-top: 14px;
}

.scene-tag {
  font-size: 0.72rem;
  text-transform: uppercase;
  letter-spacing: 0.12em;
  padding: 4px 10px;
  border-radius: 999px;
  border: 1px solid rgba(255,255,255,0.14);
  background: rgba(5,6,10,0.75);
  color: var(--muted);
  display: inline-block;
  cursor: pointer;
  text-decoration: none;
  z-index: 3;
}

.scene-project-link {
  color: inherit;
  text-decoration: none;
}

.scene-project-link:hover,
.scene-tag:hover,
.hero-bike-label:hover {
  color: var(--fg);
  border-color: rgba(255,255,255,0.28);
}

.scene-badge {
  position: absolute;
  bottom: 18px;
  right: 18px;
  font-size: 0.78rem;
  text-transform: uppercase;
  letter-spacing: 0.16em;
  padding: 4px 10px;
  border-radius: 999px;
  background: rgba(5,6,10,0.8);
  border: 1px solid rgba(255,255,255,0.16);
}

.scene-quote {
  font-size: 0.95rem;
  font-style: italic;
  color: var(--muted);
  margin-bottom: 10px;
}

.scene-quote strong {
  color: var(--fg);
  font-weight: 600;
  font-style: normal;
}

.scene-quote-attrib {
  font-size: 0.8rem;
  color: var(--muted);
}

@media (max-width: 900px) {
  .scene {
    grid-template-columns: minmax(0, 1fr);
    padding-inline: 18px;
  }
}

/* Trail progress bar */
.trail-progress {
  position: absolute;
  left: 50%;
  bottom: 16px;
  transform: translateX(-50%);
  width: min(560px, 82vw);
  height: 36px;
  display: flex;
  align-items: center;
  justify-content: center;
  pointer-events: none;
}

.trail-line {
  position: relative;
  width: 100%;
  height: 3px;
  border-radius: 999px;
  background: linear-gradient(90deg, rgba(255,255,255,0.08), rgba(255,255,255,0.02));
  overflow: visible;
}

.trail-line::before {
  /* subtle dashed overlay */
  content: "";
  position: absolute;
  inset: 0;
  border-radius: inherit;
  background-image: linear-gradient(
    90deg,
    rgba(255,255,255,0.22) 0,
    rgba(255,255,255,0.22) 8px,
    transparent 8px,
    transparent 16px
  );
  background-size: 16px 3px;
  opacity: 0.25;
}

.trail-bike {
  position: absolute;
  top: 50%;
  transform: translate(-50%, -50%);
  width: 32px;
  height: 32px;
  border-radius: 999px;
  background: radial-gradient(circle at 20% 10%, #fff 0, #ffe0d1 26%, #ff6b3d 70%, #8c2d14 100%);
  box-shadow: 0 0 0 2px rgba(5,6,10,0.9), 0 10px 25px rgba(0,0,0,0.7);
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 0.92rem;
}

.trail-bike-icon {
  font-size: 1.1rem;
  transform: translateY(0.5px);
}

.trail-marks {
  position: absolute;
  top: 50%;
  left: 0;
  width: 100%;
  transform: translateY(-50%);
  display: flex;
  justify-content: space-between;
  padding-inline: 4px;
  font-size: 0.7rem;
  text-transform: uppercase;
  letter-spacing: 0.14em;
  color: var(--muted);
}

.trail-mark {
  position: relative;
  padding-top: 5px;
}

.trail-mark::before {
  content: "";
  position: absolute;
  top: -6px;
  left: 50%;
  transform: translateX(-50%);
  width: 1px;
  height: 6px;
  background: rgba(255,255,255,0.4);
}

footer {
  padding: 32px 5vw 38px;
  font-size: 0.8rem;
  color: var(--muted);
  border-top: 1px solid rgba(255,255,255,0.06);
  background: radial-gradient(circle at top, #090b14 0, #05060a 60%);
}

footer a {
  color: var(--muted);
}

.footer-inner {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  justify-content: space-between;
  gap: 12px;
}

/* Accessibility & focus */
a:focus {
  outline: 3px solid rgba(255,107,61,0.18);
  outline-offset: 2px;
}

/* Skip link (visually hidden until focused) */
.skip-link {
  position: absolute;
  left: 8px;
  top: 8px;
  background: #fff;
  color: #111;
  padding: 8px 12px;
  border-radius: 6px;
  z-index: 9999;
  transform: translateY(-120%);
  transition: transform 0.18s ease-out;
  font-size: 0.9rem;
}
.skip-link:focus {
  transform: translateY(0%);
}

/* Visually hidden utility for labels while keeping them accessible */
.visually-hidden {
  position: absolute !important;
  height: 1px; width: 1px;
  overflow: hidden;
  clip: rect(1px, 1px, 1px, 1px);
  white-space: nowrap;
}

/* Small helper: stacked fallback for narrow screens */
@media (max-width: 640px) {
  .trail-progress { display: none; }
  .ride-track { flex-direction: column; transform: none !important; }
  .scene { flex: 0 0 auto; width: 100%; }
  .scroll-section { height: auto; }
  .scroll-container { position: static; height: auto; }
}